So you admit you're not able to compete against the national level drivers. I doubt that's only the fault of the car.
What I would be interested in would be if you swapped cars with one of them and see how close your times are. I did that once and the other driver beat my best time of the day by almost 2 seconds in my own car.
Last time I ran was around 2 years ago and I ended up 18th out of a total of 51 drivers in raw time including those running R's. I was using street tires.